Category Archives: Botany

Living in America: Part 3, The Fruited Plain

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[Apologies, readers, for once again enduring an exceptionally long, drawn-out absence in the middle of multiple post series. This is nothing new for SYDKAB, and it’s perhaps not all that surprising considering since 2012, I’ve moved to Hawai`i, started grad school, came to terms with going a different route within grad school, finished grad school, moved BACK to the mainland, gotten engaged, attempted to kick off a freelance career, and settled in a location to prepare for the birth of my first child. Here’s hoping things are a little more stable from this point out.]

This entry is Part 3 in a three-part series on organisms found in the United States in celebration of the country’s 240th birthday. Part 1, which featured some of the U.S.’s less widely-familiar vertebrate inhabitants, can be found here. Part 2 addressed a number of invertebrate species, which can be read here. This entry will go over some of the non-animal organisms that call the U.S. home, in particular, fungi and plants.

Not every life form in the USA bellows, sprints, or slinks its way across the landscape. Animals are great and all, but there is an entire world of organisms that silently spend their lives growing up from their anchored position in our sweet, sanctimonious soil, and they are no less important to the American wilderness. I’m of course talking about those multicellular cousins of the animal kingdom: fungi and plants. These organisms are far more than just idyllic backdrops for the charismatic, ambulatory stars of America’s natural history pageant, and the intricacies of their biology and diversity exceed the scope of existing in “amber waves”, or simply playing a part as filling for an insufferably Yankee Doodle dessert.

The United States is gifted with an exceptionally diverse set of biomes and ecosystems, meaning that within its borders, there are a remarkable number of species of flora….a great of them endemic to tiny, ultra-specific locations. An example of one of these local homebodies is pictured at the very top of this post. That sea of flaxen gorgeousness is made up of common monolopia (Monolopia lanceolata), a flower found in a variety of habitats from California’s Bay Area, south to the San Diego/Riverside part of the state. There are actually several species of Monolopia, and all of them are endemic to the Golden State. Appropriately enough, Monolopia is somewhat closely related to the greenswords and silverswords of Hawai`i, another set of unique plants endemic to the United States (and a remarkable example of what happens on isolated islands when evolution is given the “solitary confinement” treatment). These unassuming, attractive, yellow flowers are just the tip of the iceberg of the U.S.’s floral diversity, and included below is a small sampling of some particularly interesting stationary denizens:

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Easter Island: Ecoregion at the Edge of the World

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The popular religious holiday that occurs near the northern spring equinox goes by a number of names. Easter. Resurrection Sunday. Pasch. Whatever it is called, the majority of the world’s 2 billion or so Christians observe this holiday with regional variations of religious activities, customary foods, and symbols. Common traditional proceedings include parades and religious services, but much of the fun is directed at the youngest attendees. For small children, the holiday is the most egg-focused spectacle they’ll see until they reach adolescence and discover the decorative inspiration of Halloween. Kids spend the day giving eggs food coloring swirlies, embarking on crazed, egg-based scavenger hunts, and, for some reason, palling around with a vaguely leporid husk filled with fear-sweat and the voiceless madness that reaches out from the Void. For godless heathens such as myself, Easter mostly functions as an annual excuse to wear a classy-as-shit collared shirt, get together with fine folks, inhale brunch and booze, enthusiastically and inefficiently stagger around the grounds in a quest for plastic eggs, and to catapult my pancreas into sputtering death-fits after shamelessly replacing much of the liquid in my body with a Marshmallow Peep-derived sugar slurry.


Re-enactment: Easter Sunday 2016

The only other association I have with Easter….outside of that day of the year when I thoroughly test every major organ system in my body through the gross irresponsibility of facilitating a gastrointestinal nuclear holocaust….is a place, not an event. And because I’m a HUGE nerd, I’m obviously talking about a small island in the southeast Pacific known as Easter Island. To the Chileans, who currently have political jurisdiction over the island and categorize it as a special territory, it is “Isla de Pascua.” The original Polynesian inhabitants of the island were the first to name it, and while there is considerable debate about what exactly the island was called long before Europeans ever set foot on it, for the last century and a half, the Polynesian name for the island has been “Rapa Nui,” a term that has also come to denominate the native inhabitants of the island, and the language originally spoken there.

The South Pacific is sprinkled with a multitude of small volcanic islands and coral atolls that spread eastward from Indonesia and Australia; Fiji, Tonga, Samoa, Tokelau, the Society Islands, the Gambier Archipelago, the list goes on. The expanses of open ocean between many of these islands and island chains are not insignificant, but nowhere is the level of isolation as extreme as in Rapa Nui. Rapa Nui sits in the subtropical zone, some 27 degrees south of the Equator. It is located at the most southeasterly point of the vast, triangular Polynesian cultural region, representing the furthest eastward extent (that we know of) of Polynesian diaspora and colonization, much like how Hawai`i and New Zealand sit at the northern and southern extremes of the region, respectively.

The nearest large landmass (South America; northern Chile, specifically) is 2,300 miles (3,700 km) directly east from there, and the nearest inhabited island of any kind is Pitcairn Island…more than 1,200 miles (about 2,000 km) to the west….an island that is only about two miles across, and was perhaps only sporadically inhabited up until a few hundred years ago, when it became wholly deserted. The closest bit of land of any kind is Isla Salas y Gómez (Manu Motu Motiro Hiva), about 250 miles (400 km) to the northeast, but this tiny fleck of exposed, volcanic rock only covers about 37 acres…which means it’s only one third as expansive as the Mall of America. Thus, Rapa Nui’s closest neighbors are even more diminutive than it is, which doesn’t exactly assist with the whole extreme isolation thing. The situation reminds me of when I lived in rural, central Idaho as a child. The tiny, high-desert town I lived in (Challis) only contained about 900 rugged souls, all of which grunted out a living 150 miles away from the nearest hospital, movie theater, or fast-food franchise. However, there were towns that existed out in the Great Brown Nothing between my town and the nearest semblance of civilization. But they were puny, the barely-discernible petechiae blemishing the pale, wrinkly, boundless expanse of septuagenarian back skin that is the State of Idaho. Our closest neighbor, a hour’s track away on lonely Highway 93, was the community of Mackay…..half the size of our own town. Good ol’ Challis, Idaho wasn’t much, but it was the biggest hub by far for many, many, many miles….much like Rapa Nui.

So yes, Rapa Nui sits way out in the ass end of nowhere, atop a seamount that has formed via the Easter hotspot, an upwelling of magma below the oceanic crust that has generated a range of undersea mountains (the Nazca Ridge) as the Nazca Plate drifted above it….nothing around it for many blue, featureless miles. However, this extreme isolation wasn’t enough to keep humans away, at least not for forever.

Rapa Nui was first colonized by Polynesian settlers (probably from Mangareva (in the Gambier Archipelago) to the west, or the Marquesas in the northwest) sometime around 1200 AD or so, making it nearly the last place in the Pacific to be discovered and settled by Polynesian peoples (New Zealand was more recently settled, around 1300 AD). It was the Rapa Nui society that persisted on the island completely solo until the 1720s, when Dutch explorer Jacob Roggeveen stumbled across the place (as one does) on Easter Sunday…giving it the name “Paasch-Eyland”, Dutch for “Easter Island.” The Rapa Nui people are of course quite famous for their proclivity for carving impressively massive, stern-faced statues out of the compressed volcanic ash found on one of the island’s main volcanoes.


You know, these fellas.

Nearly 900 of these figures (called “moai”) are known to exist in modern times either on the island (or in museum collections), and can consist of nothing but the regularly referenced “Easter Island heads” or heads and bodies that are complete down to the waist or thighs. Moai are so enigmatic and stark against their often open, rolling backdrops that they’ve managed to lend inspiration (with varying levels of cultural sensitivity) to various elements of modern popular culture, from Pokemon to major settings in early Mario videogames to Spongebob’s buzzkill of a neighbor’s house.

If you’re looking at the empty, treeless plains that cover the island and thinking “how in the everloving fuck did the Rapa Nui craft and move these things around? There’s not a trace of raw materials necessary for pushing, pulling, or carving jack shit!” you and decades of archaeological pondering have something in common. The thing is, when the first Polynesian settlers arrived on Rapa Nui, the island was covered in thick, subtropical forests. Within a few hundred years, around the time Europeans first saw the island, nearly every single tree was gone. Various explanations have been thrown around as to how and why Rapa Nui’s forests vanished; the most popular of which has been that this is a story of environmental degradation on a micro-scale precipitated by human overpopulation, limited resources, and eventual societal collapse (although more recently, it’s been suggested that European-introduced disease and slavery may have been the driving factor for societal and population decline, while the rats that were stowaways with the Polynesian settlers’ canoes did short work of the island’s vegetation). Whatever the cause, the native forests of Rapa Nui are kaput, which is a damned shame considering that Rapa Nui’s extreme geographic isolation means that much of the island’s native flora and fauna were (and are, for those that haven’t yet become extinct) unique, in an ecological and evolutionary sense.

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Eucalyptus regnans, Tallest Tree in the South

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I like really tall trees.

I suppose the possession of this adoration of our planet’s living, heaven-raking spires comes as a kind of birthright. I grew up in the Pacific Northwest, an area not only richly coated with swaths of the densest temperate rainforests in the world, but also the tallest forests in the world. I came of age spending a great deal of time hiking and navigating forests largely consisting of several tree species that are among the world’s tallest. Coast redwood (Sequoia sempervirens), douglas-fir (Pseudotsuga menziesii), and Sitka spruce (Picea sitchensis) are all found in the lush coastal forests of Oregon and far Northern California where I spent many long, summer days of my youth; each of them generally regarded as being within the top five tallest tree species on the planet, based on the consistency and frequency of superlatively monstrous individuals within each. Even the “smaller” trees in the region seem to reach uniformly towering heights. Western redcedar (Thuja plicata) can top out at 200 feet (61 m) or more above the soft, spongy soil of the dark, coastal woods of Washington and Oregon. Western hemlock (Tsuga heterophylla), a very common sight in the Pacific Coast Ranges, can easily grow to some 250 feet (76 m) at its droopy crown. The bottom levels of the canopy in a Pacific Northwestern old-growth rainforest can potentially be no less than 150 feet (46 m) high, which is a value not often matched in any other forested region on Earth.

A shaggier version of myself standing with the Quinault Lake Redcedar, the largest western redcedar in the world, on Washington’s Olympic Peninsula in June 2011 (Photo credit: Werner G. Buehler)

It’s no wonder that growing up immersed in this place has left me with a love for these great trees; old-growth forests full of venerable, enormous trees are incomparably majestic places. The sense of perspective and scale that these trees provide is invariably humbling. It’s difficult not to walk alongside them in a kind of hushed reverence, as if you were traversing the floor of an ancient and solemn temple or cathedral, one crafted from humongous, gnarled pillars of wood and moss, rounded with smoothed with deep time and dark silence. The temperate rainforest springs to life in intense bursts of emerald from wherever these trees have embedded their water-ravenous feet, with lithe lances of ferns and the ghostly baubles of root-associating mushrooms erupting wherever soil space is available. These dampest and darkest of woods, blanketed from the sun a football field’s length upwards, have been described as primordial, as a place of senescence and decay, but I think this is a misplaced conceptualization. The sites where the greatest of these trees grow is positively choked with life; life that clings to and parasitizes other life, life that reaches achingly skywards in even the weakest, most diluted sunbeam to touch down on the forest floor. In my mind, these are places of as much birth and flourishing as they are museums.

This aesthetically spell-binding quality, mixed with these forests’ complex ecology and somewhat unique, insular propensity to harbor endemic species…creatures found nowhere else in the world…is what persistently attracts me back to them time and time again (and also inspires me to write about them…multiple times…because I’m a little insufferable).

It is these types of places, misty, verdant groves of titanic conifers, that come to the mind of most when they envision the world’s tallest trees…granted they call the Northern Hemisphere home. It’s somewhat widely known that California’s coast redwoods are the world’s tallest species, and across the North American continent the sheer size of Pacific Northwest forest trees is no secret…especially when compared against the far more “compact” deciduous trees that are common on the Eastern Seaboard. But a very close contender for the title of the most gravity-taunting plant in the world comes from a location not often associated with impenetrable forests. One of the tallest organisms on Earth is an altogether different kind of plant than the behemoth redwoods, and it hails from the opposite side of the globe from the dewy haunts of Cascadia…a place far more associated with rust-colored, alien deserts, blinding heat, and a faunal assemblage that constitutes the world’s largest bucket of shorts-soiling “hell fucking no.”

I’m of course talking about Australia.

Yes, Australia is a place of extremes…where the venom flows like water, the coral reefs are supersized, and summer turns the landmass into a not-so-metaphoric broiling pan of unending solar-powered punishment  (one that keeps getting hotter). From a biological perspective, Australia is a continent perpetually locked in rebellious teenager mode, deviating from the rest of the world’s biota and letting its freak flag fly proudly for millions of years in a parade of pouches, flightless birds, weird plants, fangs, spikes, and scales. It is therefore quite fitting that one of the tallest trees in the world, the only one in the top five that is not a conifer, in pure contrarian style, is Australia’s Eucalyptus regnans…the “mountain ash” or “swamp gum.”

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Evolutionary Anachronisms

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The avocado.

You may think you have a good relationship with the avocado. The buttery fruit of this plant may regularly accompany your turkey sandwich, sliced and fanned out across the bread. Or, it may serve as a hearty dip in the form of guacamole. More recently, avocado is seemingly being utilized in a greater variety of ways, being deep-fried, thrown in macaroni and cheese, and finding its way onto burgers, Subway sandwiches, and even into ice cream. You’d expect that with all this attention, our green-fleshed, knobby-skinned friend, the avocado, would be content with its current role in human culinary efforts.

However, the avocado may very well be lonely.

Despite all our affection, this loneliness stems from the avocado potentially having eyes for another. I mean this, of course, in the sense of the concept of co-evolution (which I examined in a previous post), which is directly tied to the reproductive role of the fruit itself. The main function of a fruit (a botanical fruit, typically meaning the structure derived from the reproductive tissues of the flower housing the seed(s)), is to move seeds away from the parent plant and into areas that promote growth and survival. Many types of adaptations in fruits exist to help achieve this goal of seed dispersal; from the wind-catching dual blades of maple tree fruits (known as samara), to exploiting the appetites of the ubiquitous (and notably mobile) animals in the neighborhood. This latter evolutionary strategy involves the development of fruits that enrapture animal taste buds and provide irresistible caloric value, allowing consumed seeds to travel safely inside the gut of an unwitting, far-traveling chauffeur until being excreted away from the crippling shade of the parent plant. This is called “endozoochory.”

Most endozoochorous fruits have evolved to be eaten by fairly specific animals. Predictably, fruits adapted to be taken by songbirds are going to have different physical attributes than those associated with insects or elephants. You can try and fit a peach pit through the body of a sparrow, but you aren’t going to get very far. Similarly, expecting tiny, thin-walled seeds to withstand an elephant’s battery of grinding teeth isn’t realistic either. The suite of fruit traits evolved for dispersal by a given group of animals roughly categorize into “seed dispersal syndromes.” By interpreting these syndromes, we can often get a good idea of what the primary dispersing animal, the other partner in a co-evolved relationship, is likely to be.

In light of this, it becomes obvious that despite our love of the avocado (specifically, domesticated cultivars with lots of flesh; wild avocado fruits have a thinner layer of green deliciousness surrounding that pit), it is not “meant” for human consumption and seed dispersal. Any attempt to chew up the whole fruit and swallow the massive pit is bound to land your asphyxiating ass in the cemetery. However, the situation for avocado’s seed dispersal isn’t much better in its wild Neotropical range. Many smaller animals (like monkeys) that partake in avocado consumption are “pulp thieves”, ingesting the oily layer and tossing the seed at the base of the parent tree. In fact, no native animal is known to consistently and effectively disperse wild avocado. Why then does the avocado make a big, energetically expensive fruit that doesn’t cut the mustard on dispersal? Also, who is the true “buyer” of avocado’s product?

The answer to both those questions may be that the avocado’s chief dispersal agent is extinct. Kaput. Gone. Effectively an “ex-animal.” This would mean that the avocado fruit is an evolutionary anachronism, equipped with traits fine-tuned by evolution for interaction with a species that has quite suddenly disappeared, leaving the once perfectly capable seed vessel under-appreciated and inadequately used.

“Fruit’s almost ripe, guys. Come and get it! Hello? ….Guys?!”

It’s a very serious case of being all dressed up with nowhere to go.

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The Klamath Bioregion

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When I actually get around to updating this blog I have going here, I typically spend my time talking about specific biological phenomena, or species, that go relatively underappreciated by the non-biologist public. After all, the name of this project is Shit You Didn’t Know About Biology, is it not? However, as someone with a background in evolutionary biology, as well as ecology, I can attest to the significance of communities of organisms and large scale patterning over landscapes. Our planet can be broken up into distinct ‘bioregions’ or ‘ecoregions’, which contain geographically distinct groups of communities of species, and these regions tend to be unique to other defined regions. Think of them as neighborhoods of sorts, each one defined by a specific combination of factors from local geology, geography, climate, and recent biogeography (or, the local distribution of organisms in that region; for example, you aren’t going to find tigers in the grasslands of Brazil, or sloths in the jungles of Central Africa, since a combination of evolutionary history, lineage migration, and plate tectonics has influenced the biogeography of these critters). The one I’ve chosen to talk about sits in an isolated and generally unfamiliar corner of the United States. This bioregion is very dear to me, because I spent more than three years of my life living there in high school, and although I was not there long, I was continually impressed by how special of a location it is. It is known as the Klamath Mountains ecoregion, as those mountains are a dominant feature in the region; the region, more generally, is also referred to as the Klamath Uplift, the Klamath Knot, and the Klamath-Siskiyou area. From a historical and political perspective, the region is effectively the coastal two-thirds of the proposed U.S. state of ‘Jefferson’, which straddles the current border between Oregon and California.

The map above shows some formal boundaries of designated ecoregions in the Pacific Northwest, and 78 is generally accepted as the Klamath Mountains zone. I’ve circled a slightly differently oriented area in red as to show the areas with which I’m most familiar, and additionally, because the presence of the Klamath Uplift itself influences the climate and resulting biodiversity of coastal zones (zone 1 on the map), so that the coasts of far southern Oregon and far northern California are very different from rest of the coastlines from their respective states. In blue, where the Klamath ecoregion, and its associated uplands, come closest to the Pacific, is where I went to high school; Brookings, OR. The 150 sq miles surrounding this small town, down the coast and inland, are unique even within this special ecoregion due to this close juxtaposition of these ecological entities. I feel as though this region needs some devoted attention not only because of its one-of-a-kind attributes, but because it is an almost undiscovered place. This is true of both outsiders to the Northwest (or as I like to call them, the Those That are Seriously Missing Out), as well as people that have lived in the Northwest, even within Oregon, their entire lives. Part of the reason for this is because this area is sparsely populated; the nearest large cities, like Portland and San Francisco, are hundreds of miles north and south, along narrow, ill-maintained, rain-beaten coastal roads. Simply getting there is an arduous endeavor that involves transversing harsh, forested terrain, cutting through largely uninhabited river canyons, and putt-putting down Hwy 101 on the coast, trying not to drive off a cliff in the face of Biblical-style rainstorms with violent winds. It is largely because of this lack of habitation that this area has remained so pristine and the unique biodiversity has kept intact. The coastline does attract a modest seasonal tourist population every year, because the area has a more amiable climate than areas north and south of there, and the natural beauty of the place is unparalleled and untainted by the suffocation of human influence. It is this natural beauty and ever-present access to undistilled wilderness that many that I knew that grew up there to say ‘yeah, I guess it’s pretty special.’ But this doesn’t go far enough. The Klamath ecoregion is more than special for being pretty to live, work, and recreate in. This region of the world has among one of the highest levels of species endemism on the Pacific Coast; species endemism refers to species that are found in only one, distinct geographic area and that area only, often evolved to conditions in that special little micro-range. By this definition, it is exceptionally unique, ecologically, and this distinction, I believe, is more impactful than aesthetics.

Due to its warmer climate, which has more in common with California than Oregon and the rest of the Pacific Northwest, it has been described as a ‘chunk’ of California brought up north and transplanted across the border. But this isn’t an accurate description either. The climate and geology-fueled Klamath ecoregion is wholly unlike anything found in Oregon, in California, or technically anywhere else in the world.

This region is a rugged paradise wilderness existing within the larger relative wilds of the Pacific Northwest, if that can be imagined. A land of lush forests, pristine waters, bright, hot sunshine, and the overwhelming silence of isolation from humans and their business, the Klamath bioregion is an unrecognized gem in the U.S.’s crown. The region is possibly the most enigmatic and enchantingly beautiful natural space I have ever known. And to it, the following entry will serve as my love song…

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Bioluminescence

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Bioluminescence.

One of the more intriguing (at least to me), and beautiful quirks about the evolution of life on this planet is the repeated development of bioluminescence across many different lineages. Bioluminescence is simply the ability of a living organism to produce light. If it’s alive and luminescing, boom, you’ve got an example of a complex chemical cascade that allows sacks of meat not so different from ourselves to light up like a goddamned Christmas tree. Essentially, what is happening with bioluminescence is a highly controlled chemical reaction that releases energy in the form of light emission. This can be done by the beastie itself, or by a symbiotic microorganism that has been acquired by a larger creature. It occurs in multiple kingdoms of life, in terrestrial and marine environments. If I so desired, I could ruminate tearfully on how all of Earth’s life is chemically derived from components forged in a star in a Saganesque exposition of cosmic perspective…and how in some small way, bioluminescence is the means by which stardust can light the darkness of the universe once again. But, heavy-hearted sighs and poetic attribution of consciousness to a mechanically elegant and indifferent universe are for another day, and if done in all seriousness, for another person.

The thing about bioluminescence is that often our understanding of it is limited to a few well-known examples, and without any sort of context, biological or otherwise, other than ‘that is pretty; I like it.’ And while yes, indeed, fireflies and deep-sea fish do have a magical and/or alien quality to them, there is a whole world of bioluminescing organisms that go unloved and underappreciated and denied all the badass reasons for and applications of their abilities. Bioluminescence has evolved many times, and therefore, each example tends to have its own unique story.

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Odd Gymnosperms

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Conifers.

Most of us living in North America and Europe know these as the “Christmas tree” trees. Those of us living in the Pacific Northwest know them as every single goddamn tree in sight. Towering, evergreen, and ubiquitous in environments ranging from temperate rainforest, to rocky mountaintops, to high desert and salty seashore barrens. Many of us with some life science background in high school learned that these are what are called “gymnosperms” (meaning ‘naked seed’), and are not quite like other land plants, in that they do not produce flowers, and reproduce using things like cones and copious amounts of wind-driven pollen. Due to the visibility and familiarity of conifers in our lives, and their vast economic and ecological importance (beyond the scope of being fabulous living room decorations one month of the year), cone-bearing trees like pines, firs, yews, spruces, and cypresses are the only gymnosperms that come to mind for those of us lucky enough to have a rudimentary background in the exciting field of evolutionary botany.

The reality is that a vast range of gymnosperms exist out there. Beyond the tree farm, beyond the city park, beyond the ornamental cedar in the front yard…is an entire world of alien plants that share that prehistoric, familial association with the relatively primitive conifers we all know and love.

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Fungi

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Fungi.

Quite possibly the most overlooked of the eukaryotic kingdoms. Not as mobile as their animalian close cousins, and they tend to be more discrete than the giant, showy plants. For most of us, at their best, they are an edible foodstuff, adding a bit of gummy texture to stir-fries. At their worst, they ruin an old strawberry or cause a bit of itchy feet, much to the chagrin of John Madden. They are the completely benign decomposers of the shadows, the wood-rotting, spongey, alien-like denizens of coastal forests and poorly ventilated bathrooms. Soft. Passive. Life’s unassuming and dutiful janitorial crew. Wouldn’t hurt a fly.

Oh.

The unfortunate insects above, now reduced to crumbling husks, were parasitized by a species of Cordyceps fungus. More closely allied with common bread mold than your average forest mushroom, Cordyceps make a decent living out of selectively infiltrating the bodies of various insects, growing inside of them, and eventually killing them and erupting through their exoskeletons. Some can even impact the minds of their insect hosts, making them into little zombies that position their bodies in such a way so that when they succumb to their insides being turned into a palatable slurry, the spore producing fruiting body (or “stroma”) of the fungus can have an advantageous location over the forest below, allowing for the maximum amount of exposure possible to other unwitting victims. Observe below:

Sir David Attenborough’s soothing narration, coupled with the music, make this video far more creepy than necessary. There’s something vaguely nightmarish about those wailing strings and circus-tent music playing alongside images of death-by-killer-fungus. Cordyceps are found worldwide, but enjoy higher density and diversity in the lower latitudes. As far as we know, they tend to go after insects only.

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Co-evolution

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Coevolution.

For those of us who have a basic understanding of biological evolution (and I hope that’s all of you), one of the easiest and most straightforward ways of conceptualizing the process of natural selection as it impacts evolutionary change is imagining an environmental pressure that eventually results in a genetically-based trait alteration in populations of living organisms. For example, a bunch of short-haired hamsters move into a cold area. The shortest haired individuals die off more readily than their more shaggy counterparts, selection favors longer hair, the trait increases in overall percentage in the population, bada boom you have evolution. But in reality, there is a lot more going on in nature than non-living factors impacting living things; other living things are very much a part of the environment, and are a very large component of the evolutionary trajectory of other living things. Since both co-influencing factors are of a biologic construction, reinforcing evolutionary change can occur as a response to the consequences of a relationship in both member species…this is known as coevolution. Coevolution allows the emergence of ecologically complex interdependent relationships, sometimes with many different species involved. Coevolution often results in predator-prey evolutionary dynamics, host-symbiont relationships (as well as host-parasite relationships), and a whole mess of interactions based on nothing but exploitation of an unwitting victim species.

< / coevolution intro>

Consider a flower. Most people enjoy flowers; they can be brightly colored, intricately shaped, often smell nice, and for those of us living in the seasonal latitudes, they are a symbol of the warm days of spring and summer. However, the pleasantries of a flower are not for you. Flowers do not care about you. The plant that makes the flower is doing it for reproduction, and this reproduction is almost never dependent on your swooning suspirations and giddy entrancement with color. For angiosperm (the division of plants that produce seeds and flowers) plants, flowers are the embodiment of sex. They are there to both disperse genetic material and grow fertilized offspring. This is where something called pollination syndrome comes in, and no, it’s not contagious and no it’s not what is killing all the honeybees. Pollination syndromes are essentially a suite of traits of flowers that have evolved as a response to a certain pollination vector (which could be abiotic, like wind or water, or biotic, like through living animals). The relationships with animals entirely for reproductive means allow for rampant coevolution. The difference between the biological vectors is significant because it determines many characteristics of the targeted flower. The plant has to do a good job of making a flower that attracts a certain group of pollinators, so the evolution of pollinator-flower relationships tends to drive towards the tailor-making of flowers to maximize the appeal to the vector. Most flowers we know and love are like fast-food billboard advertisements along a freeway. The sultry Carl’s Jr. billboard appeals to our desire for fatty, greasy, starchy goodness; a flower’s coloration pattern and scent tap into the sensory batteries of the bee brain.

Eat at Joe’s Rose

If Carl’s Jr. is successful, we end up making a detour, eating ourselves into a bloated and ashamed mess, and they get our money. If the flower is successful, the vector drops in for a sample of nectar, and leaves with a dusting of pollen to transmit to the next flower.

Bees get a lot of attention for their role in pollination. And they should, as they tend to pollinate many of our most important food crops…hence the anxiety about Colony Collapse Disorder. But often overlooked are the bigger, non-stinging vertebrate pollinators like birds. Flowers pollinated by birds, due to a different set of parameters for coevolution, tend to be different from insect-pollinated flowers. Bee-pollinated flowers tend to be yellow or blue with nectar guides, which are basically landing strip lights that show up as stripes only visible in the UV spectrum (which bees conveniently can see in) that say HEY BEE, THERE’S FOOD AT THE CENTER OF THIS FLOWER AND THIS IS HOW YOU GET THERE. Nectar production by the flower is moderate, as bees aren’t all that big, and they tend to be scented, as bees have finely tuned chemical sensors. With flowers that are bird-pollinated (or “ornithophilous”), a different strategy is taken. Red or orange is far more common color used to attract birds, since these stand out more readily in the vision of birds. The flowers are usually unscented, because birds have a shitty sense of smell, and making sweet-smelling compounds for no reason is counterproductive to overall fitness. Ornithophilous flowers also tend to make a LOT of nectar to keep the bird well-fed and coming back for more, hence keeping the relationship stable. Since nectar, being pure sugar, is energetically expensive, there is an evolutionary push towards trying to maximize benefit from each encounter, while minimizing the loss. Because of this, these flowers have evolved shapes that tend to be long and tubular. This forces the bird to force its face deep into the flower to get at the nectar in the back, potentially minimizing the amount it can lap up, and increasing the amount of pollen that gets all over the bird’s head. Many groups of birds have coevolved alongside this floral effort, combating this attempt to fleece them in the name of sex by evolving longer and thinner beaks and longer tongues. The most specialized nectar-feeding birds in the worlds (hummingbirds, honeycreepers, and sunbirds) all have long, curved beaks with insanely long tongues. This coevolution goes back and forth, selecting for ever longer bird beaks and tongues and ever deeper flowers. Hummingbirds and flowers have been engaged in a beautiful game of attempting to screw each other over for tens of millions of years.

Some plants have evolved to exploit the other flying vertebrates; bats. Bat-pollinated flowers tend to, of course, open at night. They are also large, white, incredibly odiferous, bell-shaped, and produce loads of nectar. The downcast bell uniquely suits the upside-down clinging of bats, the large size makes them easy to distinguish with echolocation, and seeing as how bats have an awesome sense of smell, all that sweet and sticky odor works out perfectly.

African baobab: Just for you, my web-winged friends.

Sometimes there is another level of complexity in these pollination syndromes that takes advantage of a specific dietary affiliation of their target pollinator. Instead of appearing to be an ambiguous food source, they appear to be something altogether different. One example of this are the Dracula orchids of Ecuador, of which there are many species. Dracula flowers tend to be large, drab, and in possession of a modified petal that is pale, upturned and folded to resemble a gilled mushroom. As if that wasn’t enough, the orchid steps it up a notch and also produces an aromatic compound that mimics, perfectly, the rich smell of a rainforest fungus…the same fungus that the fungus gnat uses for sustenance. The gnat follows the scent, comes across a convincing visual mimic in the warped mushroom petal, and attempts to dig in. By the time the gnat figures out it’s not on top of its favorite food, it has already been covered in the orchid’s pollen. Fungus gnats must live a pitiful and frustrating life, constantly being duped by a goddamn plant.

“I vant to take your pride and shit on your self-vorth. Ahahaha.”

Plant-animal coevolution doesn’t always have to entail trickery, callous self-interest, and feigned kindness. Sometimes what’s known as a symbiotic relationship can evolve, in which both parties legitimately benefit from the interaction, and are completely dependent on each other for survival. Individual fitness is still the ultimate factor, but a car salesman-esque swindle isn’t the primary way of getting there.

This is the bullhorn acacia (Acacia cornigera), native to much of Central America. Taxonomically, it shares a family with such familiar plants as beans, peas, lupine, and vetch; a look at the leaves provides a good hint. Anyways, the bullhorn acacia is so named for its swollen and hollowed out stipular spines, pictured above, which resemble cow horns. Most acacia trees, found in tropics worldwide, possess very bitter alkaloid compounds in their leaves which serve as a deterent to being eaten by insects and large herbivores. This species went on a different evolutionary trajectory, nixed the nasty taste, and formed a symbiotic relationship with the ant Pseudomyrmex ferruginea in order to protect itself. The ants spent a lot of time in the shelter of the hollowed out spines, and when any sort of animal interacts with the tree, be it a frog, deer, or human, they rush out in a rage and swarm and sting the unfortunate beast that brushed up against the coveted acacia. The ants pack a hell of a punch in their sting, and are more like wasps in that regard. Most herbivores learn quite quickly, of course, not to fuck around with bullhorn acacias. It is also thought that some herbivores, after interacting with these plants, learn what the alarm pheromones of the ants smells like, and give the plants quite a bit of room based on that. The ants are also so dutiful to their gracious plant host that they routinely clear away seedlings of other plants growing around the acacia that threaten to grow up and block access to sunlight. The ants do all this because their beloved acacia provides more than just a boss as hell spiny loft in the jungle to crash in; the bullhorn acacia produces protein and lipid-rich nodules on its leaflet tips called Beltian bodies (pictured below), along with a sugary nectar from glands on the leaf stalk. The ants essentially live purely on these products, and will go apeshit on any threat to their food supply. So, while the relationship works well both ways, there is some passive manipulation going on. The acacia gets a private army of hyperaggresive ant slaves by getting them hooked on readily available, energy rich food, and the ants live contently…but have to fight and die in order to get their fix.

I blame the schools.

Stepping away from plants and bugs, and towards the antagonistic predator-prey interactions, one must look on the west coast of North America, a place very dear to my heart. Anyone who has lived there undoubtably is familiar with the rough-skinned newt (Taricha granulosa), with its ubiquitous presence in rivers and streams, pebbly gray back, bright orange belly, and adorable amphibian face. As children we were wisely warned by our elders to wash our hands after handling the newts, not because they are dirty, slimy, bacteria-ridden critters…but because rough-skinned newts are among the most toxic amphibians in the U.S. They produce tetrodotoxin, which then seeps through their skin; tetrodotoxin is same toxin that pufferfish possess…and that kills a certain number of Japanese and too-ballsy-for-their-own-good tourists from fugu consumption every year. Tetrodotoxin is also used by some lethally toxic poison dart frogs. For humans, the toxin isn’t much of a concern unless it’s ingested or introduced through the mucuous membranes or through a cut. SO ATTENTION FELLOW WEST-SIDE OREGONIANS: If you are “upriver”, and you cut your hand on a blackberry bush struggling to get down to a sandbar, because you didn’t want to spill your Ninkasi or smash your Newman-O’s…you might want to think twice about handling that cute little newt you spotted on your last dive to the river bottom. Part of the reason these little guys are so damn toxic is because of this:

LITTLE BUDDY!!!! D:

Garter snakes (Thamnophis sirtalis) have a penchant for newt flesh. In theory, the tetrodotoxin messes with a sodium channel in the snake’s nerve cells, making the above dining risky, if not deadly. However, some populations have developed genetic dispositions that make them resistant to the newt’s toxin, allowing them to munch on as many squishy, defenseless newts as they want, which gives them a unique advantage over other predators, as they are the only creatures that can exploit this food resource. In areas where toxin-resistant snakes occur, there is a selective pressure on newts for more potent toxins to protect against the super-snakes. This coevolutionary back and forth, with ever-increasing toxicity and reactionary resistance evolution, goes on and on, in what is referred to as an evolutionary “arms race.”

“Vengeance will be mine…just give me a hundred generations or so.”

This has occurred for a long time, sporadically, throughout the entire range of the rough-skinned newt. The end result is, in general, a species of newt that produces toxin levels far beyond what would be necessary to kill any other predator. This was made adundantly clear in 1979 when a 29-year-old college student in Oregon (of course) died not too long after swallowing a newt on a dare at a party. So yeah, thanks a lot garter snakes. Now we Oregonians are forced to resort to boring things like goldfish to throw down the gullet on a drunken whim. There’s no telling how far this arms race will go, but given the long history of such things, I’m worrisome.

Extremes exist on the more laid back, symbiotic side of things too.

This is lichen. It looks a little like a hardy plant, or a fungus, but in reality, it’s neither. Lichen is not actual a single “thing”, but a composite organism made of a species of fungus and a separate species of green algae or a cyanobacteria. The fungal component is known as the “mycobiont” and provides the greater structure and framework for the lichen. The cyanobacteria or algae, contained inside the mycobiont itself, is the “photobiont.” The photobiont is, predictably, a photosynthesizer, and produces carbohydrates for both partners from sunlight. The mycobiont provides shelter for the photobiont, and assists in the retention of water and minerals. Lichens have evolved multiple times over the past several hundreds of millions of years, and rightfully so, as lichens tend to be highly successful in extremely dry and cold environments. They represent some of the most specialized, ancient symbiotic marriages in the history of life. And we humans think making it to our 25 year anniversaries are hard.

“You can’t expect me keep water contained with this little sugar. I have NEEDS, damnit!” “Well MAYBE if you didn’t make hyphae weren’t so fucking thick, I could actually see the sun! We’ve been over this, but nooooo, it’s like talking with a brick thallus with you!”

But even lichens may not corner the market on symbiotic supremecy. Eukaryotes, which are organisms whose cells contain membrane-bound organelles (a nucleus, chloroplasts/mitochondria, Golgi apparatus), include all multicellular life. You, me, all animals, plants, fungi, algae, and single-celled protists are all eukaryotes. They arose roughly 2 billion years ago, and the evolutionary step towards having complex, membrane-bound structures like organelles inside each and every cell is arguably one of the most significant transitions in the history of life on Earth. One theory, which is now heavily supported, is that these organelles were not just manufactured by a bacterial or archaean cell. Endosymbiotic theory posits that eukaryotic cells are derived from a collection of bacterial cells that became symbiotic upon each other deep in evolutionary time. Mitochondria could be derived from a proteobacterium that became internalized inside another bacterium, becoming a dependent “endosymbiont.” Chloroplasts could be descendents of cyanobacteria that underwent the same process. Some evidence for this comes from the fact that mitochondrial and chloroplast contain their own, distinct DNA from the main cell’s nuclear DNA. They also replicate themselves in a similar manner to bacterial cells. If endosymbiotic theory is indeed true, you and I are less a cohesive, singular organism than we ever thought. Not only are we technically a giant collective of cells masquerading as a single, whole unit…but within those cells, we may have another level of collective organization. It may be that, although we conceive of ourselves as individuals (and certainly from an evolutionary and ecological standpoint, we are), at our most basic level, we are a collection of interdependent machines, supporting each other for billions of years, with the only thing “individual” about us being the singular goal of the replication of the “main” cell’s genetic material.

All of this collective organization is driven by a little known organelle called the marxochondrion.

Coevolution adds an additional layer of complexity to evolutionary dynamics on this planet, and is responsible for the much of the diversity of life on this planet. Life has a profound impact on other life, and by driving the biosphere into dizzying heights of diversity, helps ensure the long-term survival of life on Earth.

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2014. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.